1. Field of the Invention
This invention relates to umbrellas, and more particularly, to a pivotal-coupling device for the collapsible frame structure of a self-opening umbrella for use to pivotally couple each of the framing ribs of the collapsible frame structure to the main shaft of the umbrella.
2. Description of Related Art
A collapsible umbrella (also called a foldable umbrella) allows the user to collapse the umbrella when the umbrella is not in use for easy storage or carriage. Collapsible umbrellas are typically provided with a self-opening mechanism that allows the umbrella, after being collapsed, to be opened automatically without manual effort from the user. A collapsible frame structure typically includes a frame of ribs that are coupled in a pivotable manner to the main shaft so as to allow the umbrella frame to be collapsible. A conventional pivotal-coupling device for collapsible umbrella frame structure is illustratively described in the following with reference to FIGS. 4-6.
As shown in FIGS. 4-6, the conventional pivotal-coupling device for collapsible umbrella frame structure includes a first linking member 30 affixed to the main shaft 10 of the umbrella, and a second linking member 40 affixed to one end of one framing rib 20 of the collapsible umbrella frame structure. The first linking member 30 can be pivotally coupled to the second linking member 40, thereby allowing the main shaft 10 to be pivotally coupled to the framing rib 20. The first linking member 30 includes a substantially U-shaped body 31; a pair of tubular members 32, 33 having a through hollowed inside 330, 320 allowing the main shaft 10 to insert therein; and a coupling hole 35 for pivotal coupling with the second linking member 40. Further, the first linking member 30 is formed with a pair of applying surface 321, 331 where supersonic wave bonding process can be applied so as to help secure the first linking member 30 to the main shaft 10. The second linking member 40 includes a body portion 41, a tubular portion 42, a fixed ear 43A, a bendable locking ear 43B, and a pivotal pin 44. The tubular portion 42 has a bore that allows the framing rib 20 to insert therein and fixed in position by also applying supersonic wave bonding process on the applying portion 421.
As shown in FIG. 5, during assembly, the first linking member 30 is first coupled to the second linking member 40 in such a manner that the pivotal pin 44 on the second linking member 40 passes through the coupling hole 35 in the first linking member 30. After this, as shown in FIG. 6, the bendable locking ear 43B is bent upwards to allow the hole 432 in the locking ear 43B to be coupled to the free end 441 of the pivotal pin 44. After this, the free end 441 of the pivotal pin 44 is melted by using, for example, supersonic wave bonder, into an enlarged end 441A that can help secure the locking ear 43B tightly in position. This completes the coupling of the main shaft 10 to the framing rib 20. As illustrated in FIG. 6, the main shaft 10 is pivotally about the pivotal pin 44 of the second linking member 40.
One drawback to the foregoing pivotal-coupling device, however, is that it requires the use of supersonic wave bonder to complete the pivotal coupling of the main shaft 10 to the framing rib 20, which makes the assembly work quite costly to carry out. Moreover, the forming of the bendable locking ear 43B and the hole 432 therein is quite difficult in machining, and the hole 432 can hardly be aligned precisely with the pivotal pin 44. The resultant pivotal-coupling device is therefore occasionally poor in quality that can easily break apart.